In recent years, liquid crystal display (LCD), which typifies flat panel displays, have been widely used not only in the field of small or medium-sized panel, but also in the field of large panel, such as for TV. Active-matrix type liquid crystal display apparatus is widely used in such liquid crystal display.
The display panel of an active matrix liquid crystal display apparatus includes a plurality of source bus lines (video signal lines), a plurality of gate bus lines, pixel-forming units, and others. The pixel-forming units are provided at portions where the plurality of source bus lines and the plurality of gate bus lines are crossed, thereby arranged in a matrix. Each pixel-forming unit comprises a thin film transistor, a pixel capacitor for holding pixel voltage value, and the like. A gate terminal of the thin film transistor is connected to a gate bus line that passes a portion where the gate bus line and a source bus line cross. Also, a source terminal of the thin film transistor is connected to the source bus line passing through that portion. Also, an active matrix liquid crystal display apparatus comprises a gate driver for driving the gate bus lines, a source driver for driving the source bus lines, and the like.
One source bus line is not possible to simultaneously transfer video signals representing pixel voltage values for multiple rows. Therefore, writing (charging) of video signals to pixel capacitors in pixel-forming units arranged in a matrix needs to be performed sequentially for one row at a time. Thus, the gate driver (a drive circuit) has a configuration in which more than one shift registers are connected to each other so that multiple gate bus lines are sequentially selected for a predetermined period. The gate driver, based on a plurality of clock signals, outputs a drive signal sequentially from shift registers in each row to each gate bus line (see Patent Document 1).